Standard therapy, consisting of intravenous immunoglobulin and aspirin, reduces, but does not eliminate, coronary artery aneurysms (CAAs) in patients with Kawasaki disease. Large CAAs can persist or undergo varying degrees of regression. The treatment of large CAAs using abciximab has been associated with short-term regression; however, longer term data are unavailable. We sought to obtain longer term follow-up data regarding the changes in the diameters of large CAAs in patients receiving both abciximab and standard therapy and to compare these changes to those of a similar group receiving standard therapy alone. All patients with Kawasaki disease and large CAAs (diameter >5 mm or Z score >10) treated from 1986 to 2007 were identified and divided into 2 groups. The abciximab group received abciximab plus standard therapy and the no-abciximab group received standard therapy alone. The maximum diameters of the proximal right and left anterior descending CAAs were obtained from echocardiograms. The Z scores were calculated for 3 points: the acute/subacute phase (<8 weeks) and at 1 and 3 to 5 years of follow-up. The patients in the abciximab (n = 11) and no-abciximab (n = 7) groups were similar in age, interval to treatment, gender, and largest CAA Z score at diagnosis (19.6 +/- 6.2 vs 25.8 +/- 9.5, p = 0.11). The change in CAA Z score was similar between the 2 groups at 1 year (p = 0.99). At 3 to 5 years of follow-up, compared to baseline, the abciximab group had a greater decrease in the CAA Z score than did the no-abciximab group (-14.0 +/- 4.0 vs -8.2 +/- 5.9, p = 0.04). In conclusion, abciximab treatment might be associated with vascular remodeling in patients with large CAAs.